In a film-forming apparatus for forming a thin film on a semiconductor or electronics-related machinery and tools according to, for instance, the sputtering technique, the vacuum evaporation technique, the ion-plating technique and the CVD technique, a film of a metal or a metal compound constituting a film-forming material is inevitably deposited on or adhered to certain component members of a film-forming chamber arranged within such a film-forming apparatus during a film-forming process. For this reason, the component member for the film-forming chamber comprises, for instance, a baffle plate for preventing any deposition of a film on the interior of the vacuum chamber other than a substrate, a mask which permits the deposition of a film only on the desired portions of a substrate, a tray for transporting the substrate and/or a shutter and accordingly, a film having a composition identical to that of a desired thin film (one to be deposited on the substrate) is deposited on these members.
The thickness of the film inevitably deposited on these component members for the film-forming chamber increases in proportion to the increase in the operating time. In addition, these members are in general repeatedly used after the removal of such films deposited thereon. Such deposited films may be peeled off from these members for the film-forming chamber in the form of particles due to the action of internal stresses and/or repeated thermal history, these films peeled off are then deposited on the surface of a substrate and this becomes a cause of various defects of a desired film deposited on the substrate. Accordingly, these component members for the film-forming chamber are detached from the film-forming apparatus at such a stage that the deposited film is not yet peeled off from the member, the members are then washed to thus eliminate the deposited films, these members are subsequently subjected to a surface-finishing treatment and then they can thus be reused. The cycle consisting of the foregoing steps are in general repeated at regular intervals.
There have in general been used, for instance, a valuable metal such as Al, Mo, Co, W, Pd, Nd, In, Ta, Re, Au, Pt, Se or Ag, as a film-forming material. In this connection, there has been desired for the development or establishment of any technique for recovery and recycling treatments for these film-forming materials, in order to reduce the amounts of these materials, which are not used in the film-forming processes and disposed or abandoned, to a level as low as possible.
For instance, the baffle plate is used for the prevention of the deposition of any film-forming material onto the internal wall of the apparatus other than the substrate and a variety of component members for the film-forming chamber, arranged in the film-forming apparatus, but it is presently common that the plate is reused after the removal of any deposits thereon during the film-forming stage. As methods generally used for the removal of these deposits, there have been known, for instance, a sand-blasting method; a wet etching method which makes use of an acid or an alkali; a peeling method which makes use of the hydrogen embrittlement with, for instance, hydrogen peroxide; and a method for peeling the same while making use of the electrolysis technique. In this connection, however, the baffle plate would be damaged, through the dissolution of the same, to a certain extent during the process for the removal of such deposits and therefore, this may in turn limit the number of the repeated use of the same.
In this respect, only a small amount of blasting dust is generated during the foregoing sand-blasting step and the waste fluid generated in the foregoing treatments with a liquid containing a chemical such as an acid or an alkali contains the film, which had been deposited on the foregoing component members and peeled off therefrom during the treatments, in only a low concentration. Accordingly, these materials have in general been disposed as waste materials, at present, because of an increase in the cost required for recycling the same.
Moreover, the foregoing treatment with a liquid containing a chemical not only requires the use of an expensive chemical, but also requires the expensive post-treatment of the used chemical-containing liquid. Accordingly, there has also been desired for the reduction of the amount of such a chemical-containing liquid as low as possible and this would likewise be quite favorable from the viewpoint of the prevention of any environmental pollution. Moreover, when carrying out the foregoing treatment with a chemical-containing liquid, the film-forming materials may be converted into different chemical substances through the treatments and accordingly, an additional cost would further be required for the recovery of only the film-forming materials from the deposits peeled off from the foregoing component members. For this reason, the subjects to be recovered at present are only the film-forming materials each having a unit price comparable to the recovery cost thereof.
In addition, there have conventionally been developed a variety of methods for the generation of hydrogen gas. For instance, there have been known a partial oxidation method or a reforming method which makes use of natural gases or petroleum; a method for electrolyzing an aqueous solution of NaCl or water; and a method which makes use of a hydrogen-generating alloy material (see, for instance, Patent Article 1 specified below). At present, however, there has not yet been developed any satisfactory hydrogen-generating method.
More specifically, the method which makes use of natural gases or petroleum suffers from various problems such that it never provides hydrogen gas having a high purity, that it requires the use of a high temperature on the order of 1000 to 1500° C. and that the raw materials to be used are naturally-occurring ones or fossil fuels which would be in danger of depletion in the not very distant future. In addition, the foregoing electrolysis method likewise suffers from a variety of drawbacks such that the method requires a high production cost because of the consumption of a great quantity of electric power and that even when employing the solar energy for the reduction of the production cost, the efficiency of the production thereof is very low and it requires a high facility investment. Moreover, the method using a hydrogen-generating alloy material likewise suffers from such a problem that it cannot achieve any desired low voltage to be used and any desired stability thereof.
In this respect, the higher the natural electrode potential of a material in an aqueous solution, the wider the applicable range of the anodic protection thereof and the higher the corrosion-protecting effect thereof. Accordingly, an Al—In alloy has attracted much attention because of its low potential and high stability. However, there has not yet been developed any satisfactory Al—In alloy and accordingly, there has been desired for the development of a material which permits the occurrence of a stable and long-lasting reaction which may take place at a lower potential.    Patent Article 1: Japanese Un-Examined Patent Publication 2002-161325 (Claims)